How would I get idP access tokens using something like an Istio (Envoy proxy)?

I have a working OAuth2 Proxy using OIDC to authenticate with Auth0 programmed to work with Istio for ingress. I would like to find a similar approach for the urls that require a idP access token on behalf of the user. Is there some project setup to handle this? Am I just going to have to create a custom operator for Istio and integrate it?